Examine whether contaminants in your water supply met two standards: the legal limits established by the Safe Drinking Water Act, and the typically stricter health guidelines. The data was collected by an advocacy organization, the Environmental Working Group, who shared it with The Times.

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1 contaminant below legal limits, but above health guidelines

In some states a small percentage of tests were performed before water was treated, and some contaminants were subsequently removed or diluted. As a result, some reported levels of contamination may be higher than were present at the tap.